What is the recommended management for the passage of a collecting system stone?

Management of Collecting System Stones

Alpha-blockers should be used as first-line medical expulsive therapy (MET) for stones with a high probability of spontaneous passage, while urgent decompression of the collecting system is required for septic patients with obstructing stones. 1

Assessment and Initial Management

Stone Size and Location Considerations

• Stones <10 mm have a reasonable chance of spontaneous passage
• Stones in the distal ureter have higher spontaneous passage rates than proximal stones
• Stones >10 mm typically require surgical intervention

Medical Expulsive Therapy (MET)

• Alpha blockers are the preferred agents for MET 1

  • Increase stone passage rates by 29% compared to controls 1
  • Tamsulosin, terazosin, and doxazosin are equally effective 2
  • Reduce stone passage time and limit pain 1
  • Work by relaxing ureteral smooth muscle through alpha-1 receptor blockade

• Calcium channel blockers (nifedipine) provide only marginal benefit (9% improvement) 1

Urgent Situations

• For septic patients with obstructing stones, urgent decompression of the collecting system is mandatory 1
  • Options include percutaneous drainage or ureteral stenting
  • Both are equally effective in the setting of obstructive pyelonephritis/pyonephrosis 1
  • Definitive stone treatment should be delayed until sepsis is resolved 1
  • The compromised delivery of antibiotics into the obstructed kidney necessitates drainage 1

Treatment Algorithm Based on Stone Characteristics

For Stones <10 mm:

1. Initial approach: Observation with MET (alpha blockers) 1, 3

   • Patient must have well-controlled pain
   • No clinical evidence of sepsis
   • Adequate renal functional reserve
   • Regular imaging follow-up to monitor stone position and hydronephrosis

2. If MET fails: Consider surgical intervention

   • Ureteroscopy (URS) or shock wave lithotripsy (SWL) 1
   • URS offers higher stone-free rates with a single procedure 1

For Stones >10 mm:

1. Primary approach: Surgical intervention 1

   • URS or SWL for stones ≤20 mm 1
   • PCNL for stones >20 mm 1

2. SWL should not be offered as first-line therapy for stones >20 mm 1

Special Considerations

Sepsis with Obstruction

• Urgent decompression is mandatory before stone treatment 1
• Options:
  1. Percutaneous nephrostomy (PCN): 100% technical success rate 1
  2. Retrograde ureteral stenting: 80% technical success rate 1
• Definitive stone treatment should be delayed until infection is cleared 1

Procedural Considerations

• A safety guidewire should be used for most endoscopic procedures 1
• Antimicrobial prophylaxis should be administered prior to stone intervention 1
• If purulent urine is encountered during intervention:
  • Abort the procedure
  • Establish appropriate drainage
  • Continue antibiotic therapy
  • Obtain urine culture 1

Post-Treatment Management

• Stone material should be sent for analysis 1
• Alpha-blockers and anti-muscarinic therapy may be offered to reduce stent discomfort 1
• Patients should be monitored for stone passage and resolution of symptoms

Common Pitfalls to Avoid

1. Delaying decompression in septic patients - can lead to septic shock and death
2. Blind stone extraction with a basket - should never be performed without direct ureteroscopic vision 1
3. Attempting definitive stone treatment during active infection - increases risk of sepsis
4. Failing to follow patients with periodic imaging - essential to monitor stone position and assess for hydronephrosis 1
5. Overlooking the need for stone analysis - important for preventing recurrence

By following this evidence-based approach to managing collecting system stones, clinicians can optimize outcomes while minimizing morbidity and mortality for patients with urolithiasis.